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Let f:R to R be a function defined by f(...

Let `f:R to R` be a function defined by `f(x)=(x^(2)-8)/(x^(2)+2)`. Then f is

A

one-one but not onto

B

one-one and onto

C

one but not one-one

D

neither one-one nor onto

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The correct Answer is:
To determine the nature of the function \( f(x) = \frac{x^2 - 8}{x^2 + 2} \), we need to analyze whether it is one-to-one (injective) and onto (surjective). ### Step 1: Check if the function is one-to-one (injective) A function is one-to-one if different inputs produce different outputs. To check this, we can evaluate \( f(x) \) for \( x \) and \( -x \): 1. Calculate \( f(1) \): \[ f(1) = \frac{1^2 - 8}{1^2 + 2} = \frac{1 - 8}{1 + 2} = \frac{-7}{3} \] 2. Calculate \( f(-1) \): \[ f(-1) = \frac{(-1)^2 - 8}{(-1)^2 + 2} = \frac{1 - 8}{1 + 2} = \frac{-7}{3} \] Since \( f(1) = f(-1) \) but \( 1 \neq -1 \), the function is not one-to-one. ### Step 2: Check if the function is onto (surjective) A function is onto if every possible output in the codomain is achieved by some input in the domain. The codomain given is \( \mathbb{R} \). To check if the function can take the value \( 1 \): 1. Set \( f(x) = 1 \): \[ \frac{x^2 - 8}{x^2 + 2} = 1 \] 2. Cross-multiply: \[ x^2 - 8 = x^2 + 2 \] 3. Simplifying gives: \[ -8 = 2 \] which is a contradiction. Since \( f(x) \) can never equal \( 1 \), the function does not cover all real numbers, meaning it is not onto. ### Conclusion Since the function \( f(x) \) is neither one-to-one nor onto, we conclude that: - The function is many-one (not one-to-one). - The function is into (not onto). Thus, the answer is that \( f \) is neither one-to-one nor onto. ### Final Answer The function \( f \) is neither one-to-one nor onto. ---
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OBJECTIVE RD SHARMA ENGLISH-FUNCTIONS-Chapter Test
  1. Let f : R rarr R, g : R rarr R be two functions given by f(x) = 2x - 3...

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  2. If g(x)=1+sqrtx and f(g(x))=3+2sqrtx+x then f(x) is equal to

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  3. If f(x)=(1-x)/(1+x), x ne 0, -1 and alpha=f(f(x))+f(f((1)/(x))), then

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  4. Let f:R to R be a function defined by f(x)=(x^(2)-8)/(x^(2)+2). Then f...

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  5. If f:(-oo,2]to (-oo,4] where f(x), then f ^(-1) (x) is given by :

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  6. Find the inverse of the function, (assuming onto). " " ...

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  7. f: R->R is defined by f(x)=(e^(x^2)-e^(-x^2))/(e^(x^2)+e^(-x^2)) is :

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  8. If f(x)=log((1+x)/(1-x))a n dt h e nf((2x)/(1+x^2)) is equal to {f(x)...

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  9. If f(x)=(2^x+2^(-x))/2 , then f(x+y)f(x-y) is equals to 1/2{f(2x)+f(2y...

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  10. The function f:R to R given by f(x)=x^(2)+x is

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  11. Let f:R to R and g:R to R be given by f(x)=3x^(2)+2 and g(x)=3x-1 for ...

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  12. The function of f:R to R, defined by f(x)=[x], where [x] denotes the g...

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  13. Let f(x)=x,g(x)=1/x and h(x)=f(x)g(x) . Then h(x)=1 for a.x in R b. x...

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  14. If the functions of f and g are defined by f(x)=3x-4 and g(x)=2+3x the...

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  15. If f(x)=(sin^(4)x+cos^(2)x)/(sin^(2)x+cos^(4)x)"for "x in R, then f(20...

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  16. The function f:R to R is defined by f(x)=cos^(2)x+sin^(4)x for x in R....

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  17. A = { x // x in R, x != 0, -4 <= x <= 4 and f: A -> R is defined by f...

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  18. If f: RvecR and g: RvecR are defined by f(x)=2x+3a n dg(x)=x^2+7, then...

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  19. Let f(x) be defined on [-2,2] and be given by f(x)={(-1",",-2 le x l...

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  20. The function f: R->R defined by f(x)=6^x+6^(|x|) is (a) one-one and on...

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